1. Field of the Invention
The present invention relates to an image pickup unit for an endoscope, the image pickup unit including an image pickup device including connection terminal portions on a back surface thereof.
2. Description of the Related Art
For observation of a site that is hard to observe such as the inside of a living body or the inside of a structure, an endoscope that can be introduced from the outside to the inside of the living body or the structure and includes an image pickup unit for picking up an optical image is used in, for example, the medical field or the industrial field. An image pickup unit for an endoscope includes an objective lens that forms an image of an object, and an image pickup device disposed on an image-forming surface of the objective lens, which is generally called, e.g., a CCD (charge-coupled device) or a CMOS (complementary metal oxide semiconductor) sensor. There are image pickup devices of the type in which connection terminal portions for electrical connection with a substrate is provided on a back surface on the opposite side of a surface on which light from the image pickup device is incident (light-receiving surface) in order to reduce the mounting area of the substrate. For example, Japanese Patent Application Laid-Open Publication No. 2007-73958 discloses an image pickup device package with connection terminal portions provided on a back surface thereof. Use of such image pickup device including connection terminal portions on a back surface thereof enables mounting area reduction. Where an image pickup device including connection terminal portions on a back surface thereof such as disclosed in Japanese Patent Application Laid-Open Publication No. 2007-73958 is used in an image pickup unit for an endoscope, a form in which the image pickup device is mounted on a flexible printed wiring board, the flexible printed wiring board is flexed so as to extend rearward (direction opposite to an object) along an optical axis and electric cables disposed inside the endoscope are connected to distal end portions of the flexed parts of the flexible printed wiring board may be employed. As described above, flexing a flexible printed wiring board with an image pickup device mounted thereon so as to extend rearward enables reduction in area of projection of an outer shape of the image pickup unit on a planar surface that is perpendicular to an optical axis.